<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    *{
      padding: 0;
      margin: 0;
    }
    div{
      height: 3000px;
      background: darkcyan;
    }
    p{
      width: 100px;
      height: 100px;
      background: red;
      position: absolute;
      bottom: 0;
    }
  </style>
</head>
<body>
  <div></div>
  <p></p>
</body>
</html>